Frequency and associated factors of accommodation and non-strabismic binocular vision dysfunction among medical university students

AIM: To investigate the frequency and associated factors of accommodation and non-strabismic binocular vision dysfunction among medical university students. METHODS: Totally 158 student volunteers underwent routine vision examination in the optometry clinic of Guangxi Medical University. Their data were used to identify the different types of accommodation and non-strabismic binocular vision dysfunction and to determine their frequency. Correlation analysis and logistic regression were used to examine the factors associated with these abnormalities. RESULTS: The results showed that 36.71% of the subjects had accommodation and non-strabismic binocular vision issues, with 8.86% being attributed to accommodation dysfunction and 27.85% to binocular abnormalities. Convergence insufficiency (CI) was the most common abnormality, accounting for 13.29%. Those with these abnormalities experienced higher levels of eyestrain (chi(2)=69.518, P<0.001). The linear correlations were observed between the difference of binocular spherical equivalent (SE) and the index of horizontal esotropia at a distance (r=0.231, P=0.004) and the asthenopia survey scale (ASS) score (r=0.346, P<0.001). Furthermore, the right eye's SE was inversely correlated with the convergence of positive and negative fusion images at close range (r=-0.321, P<0.001), the convergence of negative fusion images at close range (r=-0.294, P<0.001), the vergence facility (VF; r=-0.234, P=0.003), and the set of negative fusion images at far range (r=-0.237, P=0.003). Logistic regression analysis indicated that gender, age, and the difference in right and binocular SE did not influence the emergence of these abnormalities. CONCLUSION: Binocular vision abnormalities are more prevalent than accommodation dysfunction, with CI being the most frequent type. Greater binocular refractive disparity leads to more severe eyestrain symptoms.